The present invention relates to a self-winding watch, particularly, but not exclusively, a watch of the extra thin type, that is to say a watch in which the distance between the back of the case and the glass is as small as possible.
Self-winding watches have been known for a long time. They differ from ordinary mechanical watches in that they comprise a winding weight mounted for oscillating movement about a pivotal axis which is perpendicular to the back of the watch and a gear train which transmits the energy produced by the oscillation of the winding weight of the spring barrel.
For example, Swiss Pat. Nos. 610,178 and 198,991 describe such watches. In these two cases, the watch comprises a plate carrying the usual parts of the movement of an ordinary mechanical watch and, beneath this plate, the winding weight. In the case of Swiss Pat. No. 610178, the winding weight is mounted for pivotal movement on a pivot pin rigid with a winding plate. In the case of Swiss Pat. No. 198,991, the pivotal axis of the winding weight is mounted between the supporting plate of the movement and the back of the case. In these two cases, the winding weight oscillates around an axis which coincides with the axis of watch hands. It is therefore superimposed on the ordinary movement of the watch and in its pivotal movement, the winding weight occupies a whole sector of the interior volume of the watch case. This obviously results in a substantial increase in the thickness of the automatic watch as compared with the thickness that an ordinary watch of the same type would have. It likewise is known to juxtapose the movement and the winding weight in a common plane. However, the winding energy is then weak and the dimensions of the watch, as seen in plan, are considerably increased.
Now, it is clear that the present tendency in the horological industry is to produce relatively flat, thin watches. In fact, considerable efforts have been made during the last few years by designers to reduce the thickness of watches, whether they be electronic watches or mechanical watches. Moreover, it is equally clear that the considerable development of electronic watches has caused the user to become accustomed to not having to wind his watch every day. Hence the interest is making very thin self-winding mechanical watches.